Field of the Invention
The invention relates in general to elevator systems, and more specifically to a speed pattern generator for a construction elevator car.
Description of the Prior Art
When a building is constructed having a large number of floors, a temporary elevator car is provided for men and tools for use during the construction phase. The construction elevator car may utilize an elevator drive machine which will subsequently be used in the completed building for driving a permanent elevator car. The conventional automatic elevator controls, however, including the speed pattern generator and floor selector, cannot be used during the construction phase because the apparatus which provides signals for the proper operation of these controls is in the process of being installed.
In the prior art, the construction elevator car is provided with manually operated controls, such as pushbuttons, or a car switch. These manually operated controls include positions for leveling and running speeds. An auxiliary control box with as many as twenty electromechanical relays provides a speed pattern for the drive machine in response to the manipulation of the manually operated controls. When the operator desires to move the car upwardly or downwardly, a switch is actuated, which is associated with the selected travel direction, to provide a low speed pattern for smoothly starting the car from rest, and then a second switch is actuated to provide the acceleration and maximum speed portions of the speed pattern. When the desired stopping point is approached, the operator manually selects the deceleration portion of the speed pattern, and finally the leveling speed pattern for adjusting the car position relative to the level of the stopping floor.
While the speed pattern generator for construction elevator car switch control is simple in function, since the "feedback" is provided by an operator, the prior art relay controls for providing this simple function are relatively complex and costly. Further, the acceleration and deceleration ramps in these prior art controls are not linear, as capacitors are normally utilized which provide exponential curves.
Thus, it would be desirable to provide a new and improved speed pattern generator for use with manually operated construction elevator car control, which is less complex and less costly than prior art construction elevator car controls. It would also be desirable to provide an improved speed pattern for construction elevator car use, wherein the acceleration and deceleration portions of the speed pattern are linear. Finally, these functional and cost improvements in the speed pattern generator must be accomplished without deleteriously affecting the operational safety of the system.